This invention relates to a dilatation balloon catheter, useful for medical procedures such as angioplasty, which permits fluid flow, e.g., perfusion (blood flow), around the outer peripheral surfaces of the balloon when the latter is inflated and in contact with surrounding surfaces such as the inner lining of the walls or the atheromatous plaque of a blood vessel (artery or vein) such as a coronary artery, as well as to methods of making and using the same.
Dilatation balloon catheters are well known and used daily in medical practice for life-saving coronary angioplasty procedures wherein atheromatous plaque adhering to a blood vessel wall and blocking or restricting blood flow therein is compressed to reestablish and/or increase blood flow by dilating the lumen of the artery. Compression of the plaque is effected by inflation of the balloon while it is positioned in the blood vessel so that it is located adjacent to and surrounded by the plaque.
Depending on the location of the plaque and the size of the blood vessel, a pre-shaped and pre-dimensioned catheter having a pre-shaped and pre-dimensioned inflatable balloon adhered thereto (by fluid seals), is selected. The interior of the catheter typically possesses two lengthwise channels (lumen): one for fluid inflation of the generally tubular shaped balloon (e.g., to an inflated diameter of 1-7 mm, larger or smaller diameters being possible) with which it is in sealed communication, and the other for insertion of a guidewire running the full length of the catheter to assist in positioning it during a medical operation.
Many such catheters have been disclosed as well as details of construction, methods of preparation and methods of use. See, e.g., the disclosures of U.S. Pat. No. Reissue 33,166 and U.S. Pat. Nos. 4,169,263, 4,323,071, 4,411,055, 4,571,240, 4,573,470, 4,582,181, 4,597,755, 4,616,653, 4,619,263, 4,638,805, 4,641,654, 4,664,113, 4,692,200, 4,748,982, 4,771,776, 4,771,778, 4,775,371, 4,782,834, 4,790,315 and 4,793,350, all of whose entire disclosures are incorporated by reference herein.
One of these references addresses the problem of occlusion of blood flow during an angioplasty procedure. See U.S. Pat. No. 4,790,3I5. As noted therein (column 1), during an angioplasty procedure, blood flow is cut off during the period of time the balloon remains inflated. As a result, the myocardium becomes ischemic with potentially serious consequences and the patient experiences chest pain. Thus, inflation duration must necessarily be relatively short, e.g., typically less than 180 seconds, commonly less than 150 seconds. Longer inflation times would be very desirable since better plaque compression could be effected, thereby increasing the probability of a successful procedure. Moreover, higher risk patients (e.g., those for whom any duration of blood occlusion in the particular vessel involved is an especially dangerous event) for whom angioplasty is contraindicated could have access to this valuable procedure.
U.S. Pat. No. 4,790,315 attempts to solve the blood flow occlusion problem by providing a lumen or channel inside the length of the body of the catheter between the proximal and distal ends of the catheter shaft. A plurality of openings in the side wall of the catheter on the proximal and distal sides of the balloon provide blood flow past the balloon through this lumen. However, this design has siqnificant drawbaoks. For example, the blood flow provided is relatively small, e.g., only 60-70 ml/min., significantly less than normal flow (e.g., 100-120 ml/min. for coronary arteries). Moreover, the profile of this design (i.e., total cross-sectional diameter of the catheter shaft) is much larger than that of a normal catheter due to the need for a large lumen to accommodate the resultant blood flow volume. Such a high profile catheter itself represents a danger, e.g., even of occluding or seriously impeding blood flow, for many patients, significantly lessening the applicability of its limited advantages to both a wide cross-section of patients and to various complexities of obstructions. Moreover, even where it can be employed, this prior art catheter is bulky and makes it difficult to cross blockages and/or access lesions in distal vasculature.
Thus, there remains a need for an improved dilatation balloon catheter, e.g., which permits continued blood flow when the balloon is inflated in a blood vessel, has an optimally low profile, and enhances patient safety and availability of angioplasty and other balloon catheter-based procedures to a wider class of patients, inter alia.